Polylactic acid material resistant to normal and low temperature impact and preparation method thereof

Abstract

The invention discloses a polylactic acid material resistant to normal low temperature impact and a preparation method thereof, wherein the polylactic acid material is prepared from polylactic acid resin, toughening agent, antioxidant, and nucleating agent, and the toughening agent is a mixture of hydrogenated styrene-butadiene-styrene, ethylene butyl acrylate copolymer and high-density polyethylene. The polylactic acid material resistant to normal low temperature impact of the present invention is biodegradable, and also has good normal low temperature impact performance, and the normal low temperature impact performance is significantly improved. Its preparation method has low requirements on equipment, simple process, and the equipment used is all commonly used polymer processing equipment, without the increase of additional cost, which is conducive to industrial production.

Description

Technical Field

[0001] The invention belongs to the field of materials, and particularly relates to a polylactic acid material resistant to normal and low temperature impact and a preparation method thereof. Background Art

[0002] In response to global warming, more and more studies have shown that global warming can be completely slowed down by controlling carbon dioxide emissions. The fully biodegradable polylactic acid resin, whose synthetic raw materials (lactic acid) come from animals and plants, is highly praised for its preparation process of reverse solidification of carbon dioxide. However, polylactic acid resin has poor basic physical properties and poor impact properties at room and low temperatures, and its practical application value is not high. Therefore, it is hoped that the actual application needs can be met by toughening polylactic acid resin.

[0003] At present, some research has been done on the existing polylactic acid materials resistant to normal and low temperature impact, for example: Chinese patent CN113604020A discloses a method for preparing high-toughness polylactic acid, which belongs to the technical field of preparing toughened and modified polylactic acid. The high-toughness polylactic acid is prepared by melt blending polylactic acid as raw material, polypropylene carbonate grafted maleic anhydride obtained by solid phase grafting method as toughening agent, and triethyl citrate as compatibilizer; Chinese patent CN113501942A discloses a polylactic acid degradable toughening modifier and its preparation method, the main steps of which are as follows: step (1) firstly initiates the ring-opening polymerization of lactide by an initiator to obtain a polylactic acid polyol prepolymer, step (2) uniformly mixes ε-caprolactone monomer and lactide monomer and adds them to the prepolymer, and initiates random polymerization of caprolactone and lactide by the hydroxyl group in the prepolymer to obtain a polylactic acid transparent toughening modifier. The random copolymerization of ε-caprolactone and lactide improves the flexibility of the material while reducing the problem of decreased material transparency due to crystallization and compatibility. The material has good compatibility with polylactic acid and low mobility and permeability. Chinese patent CN 112409577 A discloses a method for preparing a butyl rubber / polylactic acid graft polymer, comprising the following steps: a. preparing a butyl rubber solution; b. adding an epoxidation reagent to the butyl rubber solution to generate epoxidized butyl rubber; c. preparing the epoxidized butyl rubber into an epoxidized butyl rubber solution, adding an acidic ring-opening reagent to generate hydroxylated butyl rubber; d. preparing the hydroxylated butyl rubber into a hydroxylated butyl rubber solution, adding lactide and a polymerization catalyst under the protection of an inert atmosphere to generate a graft copolymer of butyl rubber and polylactic acid.

[0004] However, the above-mentioned published literature reports all point out that pure polylactic acid materials have poor low-temperature impact properties, and the impact at room temperature (23°C) is less than 3kJ / m 2 , low temperature (-30℃) impact <1kJ / m 2 , which cannot fully meet the actual application needs. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a polylactic acid material resistant to normal and low temperature impact and a preparation method thereof, wherein the composite material has good normal and low temperature impact resistance.

[0006] The specific technical solutions for achieving the above-mentioned invention objectives include the following:

[0007] A polylactic acid material resistant to normal and low temperature impact, characterized in that the composite material is prepared from the following raw materials in parts by weight:

[0008]

[0009] The toughening agent is a mixture of hydrogenated styrene-butadiene-styrene (SEBS), ethylene butyl acrylate copolymer (EBA) and high-density polyethylene (HDPE).

[0010] In a further embodiment, the mass ratio of the ethylene butyl acrylate copolymer, hydrogenated styrene-butadiene-styrene and high-density polyethylene is 4-8:8-12:6-10, preferably 6-8:8-12:8-10.

[0011] In a further embodiment, the molecular weight of the polylactic acid resin is 50,000 to 100,000 g / mol.

[0012] In a further embodiment, the antioxidant is a compound of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (1010) and n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (1076) in a weight ratio of 0.8 to 1.2:1.

[0013] In a further embodiment, the nucleating agent is an α-crystalline nucleating agent.

[0014] Another object of the present invention is to provide a method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact, which is obtained by mixing polylactic acid resin, toughening agent, nucleating agent and antioxidant, and then melt-extruding and granulating through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are: the temperature of zone one is 150°C to 180°C, the temperature of zone two is 160°C to 190°C, the temperature of zone three is 170°C to 200°C, the temperature of zone four is 180°C to 200°C, the temperature of zone five is 180°C to 200°C, the temperature of zone six is ​​180°C to 200°C, the temperature of zone seven is 180°C to 200°C, the temperature of zone eight is 180°C to 200°C, the die head temperature is 190°C to 210°C, the screw speed is 200rpm to 400rpm, and the ratio L / D of screw length L to diameter D is 35 to 45.

[0015] In a further embodiment, the die head temperature of the horizontal twin-screw extruder is 190°C to 210°C, the screw speed is 200rpm to 400rpm, and the screw length-diameter ratio L / D is 35 to 45. The screw shape of the horizontal twin-screw extruder is a single-thread screw, and a group of kneading blocks are arranged on the screw.

[0016] In some embodiments, the process parameters of the horizontal twin-screw extruder include: the temperature of zone 1 is 155℃~175℃, the temperature of zone 2 is 165℃~185℃, the temperature of zone 3 is 175℃~195℃, the temperature of zone 4 is 185℃~195℃, the temperature of zone 5 is 185℃~195℃, the temperature of zone 6 is 190℃~200℃, the temperature of zone 7 is 190℃~200℃, the temperature of zone 8 is 190℃~200℃, the die head temperature is 195℃~205℃, and the screw speed is 300rpm~400rpm.

[0017] The polylactic acid resin in the present invention is preferably a polylactic acid resin synthesized by fermentation of animal and plant resources. The molecular weight is selected to be 10000-15000 g / mol. If the molecular weight is too low, it is not conducive to material molding and processing, and its basic physical properties are poor. If the molecular weight is too high, the toughening agent cannot achieve the desired toughening effect.

[0018] The invention selects a mixture of hydrogenated styrene-butadiene-styrene (SEBS), ethylene butyl acrylate copolymer (EBA) and high-density polyethylene (HDPE) to toughen the polylactic acid resin, wherein SEBS can effectively improve the low-temperature impact performance of the polylactic acid resin; while EBA toughens the room-temperature impact performance of the polylactic acid resin, the acrylate polar groups contained in EBA have good compatibility with polylactic acid and can play a certain compatibility effect; HDPE and hydrogenated styrene-butadiene-styrene (SEBS) work synergistically to significantly provide high normal-low impact toughness of polylactic acid.

[0019] The addition of nucleating agent can accelerate the crystallization of polylactic acid and ensure the stability of physical properties. The compounding of antioxidant 1010 and antioxidant 1076 ensures the long-term thermal stability of polylactic acid material that is resistant to normal and low temperature impact.

[0020] Therefore, compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In the present invention, hydrogenated styrene-butadiene-styrene (SEBS), ethylene butyl acrylate copolymer (EBA), and high-density polyethylene (HDPE) are selected as toughening agents, and the ratio between the toughening agents is controlled to prepare a polylactic acid material resistant to normal low temperature impact. The polylactic acid material resistant to normal low temperature impact is biodegradable and has good normal low temperature impact performance, with a tensile strength of >50MPa and a normal temperature notched impact strength of >25kj / m 2, low temperature notched impact strength>4.0kj / m 2 , the normal and low temperature impact properties are significantly improved.

[0022] 2. The method for preparing the polylactic acid material resistant to normal and low temperature impact of the present invention has low requirements on equipment and a relatively simple process. The equipment used are all commonly used polymer processing equipment, without increasing additional costs, and is conducive to industrial production. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0024] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0025] The inventors of the present invention have found in their research that the toughening agents of polylactic acid resin, such as EBA / SEBS / HDPE, have poor toughening effects on polylactic acid resin when added alone. This is mainly because the above-mentioned toughening agents have different polarities with polylactic acid resin, the toughening agents have poor compatibility with polylactic acid resin, and the toughening agent phase size is too large, which leads to a decrease in the normal low temperature impact absorption capacity. In the present invention, hydrogenated styrene-butadiene-styrene (SEBS), ethylene butyl acrylate copolymer (EBA), and high-density polyethylene (HDPE) are selected as toughening agents. The toughening agent and polylactic acid are intertwined, and the toughening agent size is further refined. Therefore, the normal low temperature impact performance of the composite material is significantly improved.

[0026] The raw materials used in the present invention are all commercially available. The specific raw materials used in the embodiments and comparative examples are as follows:

[0027] Polylactic acid resin: its molecular weight is 50000-100000 g / mol, selected from Nature Works.

[0028] Hydrogenated styrene-butadiene-styrene SEBS: H1062, selected from Asahi Kasei Corporation.

[0029] Butyl acrylate copolymer EBA: 34035, selected from DuPont.

[0030] High-density polyethylene HDPE: T800, selected from CNOOC and Shell.

[0031] In the following examples and comparative examples, the antioxidants used are antioxidant 1010 and antioxidant 1076 in a weight ratio of 1:1, wherein antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) is selected from BASF; antioxidant 1076 (n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) is selected from BASF.

[0032] In the following examples and comparative examples, the nucleating agent used is NA-11 (α-crystalline nucleating agent), which is selected from ADK Company.

[0033] The present invention is described in detail below with reference to specific embodiments and comparative examples.

[0034] Example 1

[0035] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0036]

[0037] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0038] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0039] Example 2

[0040] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0041]

[0042] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0043] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0044] Example 3

[0045] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0046]

[0047] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0048] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0049] Example 4

[0050] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0051]

[0052] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0053] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0054] Example 5

[0055] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0056]

[0057] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0058] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0059] Example 6

[0060] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0061]

[0062] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0063] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0064] Example 7

[0065] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0066]

[0067] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0068] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0069] Example 8

[0070] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0071]

[0072] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0073] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0074] Example 9

[0075] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0076]

[0077] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0078] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0079] Example 10

[0080] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0081]

[0082] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0083] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0084] Embodiment 11

[0085] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0086]

[0087] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0088] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0089] Comparative Example 1

[0090] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0091] Polylactic acid resin 100 parts

[0092] 0.4 parts of antioxidant

[0093] 0.3 parts of nucleating agent.

[0094] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0095] After the polylactic acid resin, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are: the temperature of zone 1 is 170°C, the temperature of zone 2 is 175°C, the temperature of zone 3 is 180°C, the temperature of zone 4 is 185°C, the temperature of zone 5 is 190°C, the temperature of zone 6 is 190°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of screw length L to diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0096] Comparative Example 2

[0097] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0098]

[0099] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0100] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0101] Comparative Example 3

[0102] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0103]

[0104]

[0105] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0106] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0107] Comparative Example 4

[0108] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0109]

[0110] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0111] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0112] Comparative Example 5

[0113] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0114]

[0115] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0116] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0117] Comparative Example 6

[0118] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0119]

[0120] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0121] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0122] Comparative Example 7

[0123] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0124]

[0125] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0126] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0127] Comparative Example 8

[0128] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0129]

[0130] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0131] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0132] Comparative Example 9

[0133] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0134]

[0135] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0136] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0137] Comparative Example 10

[0138] The polylactic acid material resistant to normal and low temperature impact described in this embodiment is prepared from the following raw materials in parts by weight:

[0139]

[0140] The method for preparing the above-mentioned polylactic acid material resistant to normal and low temperature impact comprises the following steps:

[0141] After the polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed, they are melt-extruded and granulated through a horizontal twin-screw extruder; the process parameters of the horizontal twin-screw extruder are as follows: the temperature of the first zone is 170°C, the temperature of the second zone is 175°C, the temperature of the third zone is 180°C, the temperature of the fourth zone is 185°C, the temperature of the fifth zone is 190°C, the temperature of the sixth zone is 190°C, the temperature of the seventh zone is 195°C, the temperature of the eighth zone is 200°C, the die head temperature is 200°C, and the screw speed is 300rpm. The screw shape of the parallel twin-screw extruder is a single-line thread; the ratio of the screw length L to the diameter D L / D is 40; and a group of kneading block areas are provided on the screw.

[0142] The following is a table of raw material compositions of Examples 1-11 and Comparative Examples 1-10.

[0143] Table 1 List of weight parts of raw materials for examples and comparative examples

[0144]

[0145]

[0146] Remarks: A: EBA, B: SEBS, C: HDPE.

[0147] The polylactic acid materials resistant to normal and low temperature impact prepared in the above examples and comparative examples were subjected to the following performance tests:

[0148] Tensile properties: tested according to GB / T1040 standard;

[0149] Impact performance: tested according to GB / T1843 standard;

[0150] The performance test results are shown in Table 2.

[0151] Table 2 Performance of polylactic acid materials resistant to normal and low temperature impact in the embodiments and comparative examples

[0152]

[0153]

[0154] Embodiments 1 to 11 are polylactic acid materials resistant to normal and low temperature impact prepared by adjusting the ratio of toughening agent A / B / C. It can be seen from Table 2 that the toughening agents are compounded with ethylene butyl acrylate copolymer, hydrogenated styrene-butadiene-styrene and high-density polyethylene (EBA:SEBS:HDPE) in a mass ratio of 4 to 8:8 to 12:6 to 10, which can significantly improve the normal and low temperature impact properties of the polylactic acid material; when the mass ratio of ethylene butyl acrylate copolymer, hydrogenated styrene-butadiene-styrene and high-density polyethylene is 6 to 8:8 to 12:8 to 10, the normal and low temperature performance of the polylactic acid material resistant to normal and low temperature impact is significantly improved. This is because the structure of SEBS itself is a multi-arm star copolymer, in which the EB (hydrogenated diene) block has a very low glass transition temperature (-30°C), low resilience and high mechanical damping, so that the SEBS block copolymer has good low temperature performance and vibration absorption ability. The butyl acrylate contained in EBA is a polar group, which increases the entanglement of the two-phase molecular chains and plays a role in increasing the volume. HDPE has good compatibility with SEBS and EBA, and can give both of them a more efficient toughening effect.

[0155] Comparative Example 1 does not add any toughening agent, and its room temperature notched impact strength (23°C) and low temperature notched impact strength (-30°C) are significantly reduced compared with Examples 1-11.

[0156] Comparative Examples 2 to 10 are different toughening agents added separately, and the addition amount is changed at the same time. The room temperature notched impact strength (23°C) and low temperature notched impact strength (-30°C) are improved compared with Comparative Example 1, but the improvement is not obvious. Among them, the room temperature notched impact strength (23°C) and low temperature notched impact strength (-30°C) of Examples 1-11 are better than those of Comparative Examples 2-10, and the difference is obvious. It shows that the effect of the compound toughening agent EBA / SEBS / HDPE is significantly better than that of adding them separately.

[0157] In summary, the present invention adopts a specific toughening agent and controls the appropriate ratio between the toughening agents to prepare a normal low temperature impact resistant polylactic acid material having good normal low temperature impact resistance and good mechanical properties.

[0158] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0159] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A polylactic acid material resistant to normal and low temperature impact, characterized in that: The polylactic acid material is prepared from the following raw materials in parts by weight: The toughening agent is a mixture of ethylene butyl acrylate copolymer, hydrogenated styrene-butadiene-styrene and high-density polyethylene in a mass ratio of 6-8:8-12:8-10; The total amount of the polylactic acid resin and the toughening agent is 100 parts.

2. The polylactic acid material resistant to normal and low temperature impact according to claim 1, characterized in that: The molecular weight of the polylactic acid resin is 50,000 to 100,000 g / mol.

3. The polylactic acid material resistant to normal and low temperature impact according to claim 1, characterized in that: The antioxidant is a compound of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate in a weight ratio of 0.8 to 1.2:

1.

4. The polylactic acid material resistant to normal and low temperature impact according to claim 1, characterized in that: The nucleating agent is an α-crystal nucleating agent.

5. The method for preparing a polylactic acid material resistant to normal and low temperature impact according to any one of claims 1 to 4, characterized in that: The polylactic acid resin, toughening agent, nucleating agent and antioxidant are mixed and then melt-extruded and granulated through a horizontal twin-screw extruder; The process parameters of the horizontal twin-screw extruder are as follows: the temperature of zone one is 150°C to 180°C, the temperature of zone two is 160°C to 190°C, the temperature of zone three is 170°C to 200°C, the temperature of zone four is 180°C to 200°C, the temperature of zone five is 180°C to 200°C, the temperature of zone six is ​​180°C to 200°C, the temperature of zone seven is 180°C to 200°C, the temperature of zone eight is 180°C to 200°C, the die head temperature is 190°C to 210°C, the screw speed is 200rpm to 400rpm, and the ratio L / D of screw length L to diameter D is 35 to 45.

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